This problem seems to have been fixed. MyFlow is working fine again in my environment.
I hope everyone else has also experienced an improvement.
My sincere thanks go to the Opera development team.
Thank you.
Opera One(version: 119.0.5497.88)(JPN)
Windows 11 Pro 64-bit 24H2(JPN)
Operating system build 26120.4520
Experience Pack of Windows features 1000.26100.154.0